In the recent decades, television cable networks were built up in numerous countries. These television cable networks traditionally serve as uni-directional broadband distribution networks, wherein a certain number of different channels, each reserved for a specific television (or radio) signal, are provided. The television signals are distributed to a plurality of television terminals. The subscribers then might each select one certain program out of said programs by switching his terminal to a corresponding frequency.
In the last years, efforts have been made to realise dialog services within said networks, especially to offer so-called video-on-demand services. In those services, the subscribers may select specific videos to be received at a selected time. However, the provision of a return channel for enabling a bi-directional information exchange between a subscribers (cable TV) terminal and a video server requires a cost intensive upgrade of existing broadband distribution networks.
An alternative solution to the provision of a return channel within existing uni-directional networks (distribution networks) is to use an existing communication network different from the distribution network for the realisation of a backward channel. In a simple realisation, a subscriber manually connects to a video server by means of the public telephone network. In WO 98/24238, a more sophisticated solution is proposed to use the a public telephone network for realising a backward channel. Therefore, a television digital receiver or a so-called Set Top Box is provided with a wireless transmitter for transmitting backward commands via said telephone network to a video (data) server for selection of videos. The subscriber may select a video from a menu displayed on the television screen and inputs that choice by means of a subscriber interface of the Set Top Box. Said Set Top Box then automatically connects to the respective video server and transmits that choice via said mobile telephone network.
The internet is increasingly used for distribution of real time data streams. For this purpose, protocols like the real time protocol (RTP) proposed by the IETF and further control and signalling protocols have been developed. However, the access to the internet often only allows only for a very limited bit rate, that is not sufficient for the distribution of high quality real time media data.
It is an object of the invention to establish a method and corresponding devices allowing for high quality multimedia distribution multimedia servers using bi-directional communication protocols to receiving terminals connected to a unidirectional distribution network.